In short: The Impact Factor, CiteScore and h-index are citation-based metrics. They can be useful for comparison within a field, but they measure citation activity — not the quality of an individual paper — and many legitimate journals, especially newer ones, do not have them yet.
Why metrics exist — and why to be cautious
Research metrics try to summarise citation activity in a single number. They are convenient, but they are frequently misused — for example, to judge an individual paper or researcher by the journal it appeared in. Understanding what each metric actually measures helps you use it responsibly.
Journal Impact Factor (JIF)
Published by Clarivate in the Journal Citation Reports, the Impact Factor is a journal-level average: the citations in a given year to the articles a journal published in the previous two years, divided by the number of those articles. It is calculated only for journals indexed in Web of Science, so many journals do not have one. Typical values vary widely by field, so figures are only comparable within the same discipline.
CiteScore
Published by Elsevier and based on the Scopus database, CiteScore is a similar journal-level average but uses a four-year citation window. It is calculated only for journals indexed in Scopus.
h-index
The h-index is an author-level (and sometimes journal-level) metric: an h-index of h means h outputs have each been cited at least h times. It combines productivity and citation impact in one number, but it inevitably favours longer, established careers and differs greatly between fields.
The limits of metrics
- They measure citations, not quality; a highly cited paper is not necessarily a good one.
- They are field-dependent and should never be compared across disciplines.
- A journal-level metric says nothing about an individual article.
- Initiatives such as the San Francisco Declaration on Research Assessment (DORA) call for research to be judged on its own merits, not on journal metrics.
A note for authors choosing a journal
Metrics are one input, not the decisive one. When choosing a journal, scope, audience, peer-review quality, ethics and legitimacy matter more. New but legitimate journals are still building the citation record on which these metrics depend, so the absence of a metric is not, by itself, a mark against a journal.
Key takeaways
- Impact Factor and CiteScore are journal-level citation averages from different databases and time windows.
- The h-index is an author-level measure of productivity and citation.
- Metrics measure citations, not quality, and are field-dependent.
- Judge research on its merits; many legitimate journals have no metric yet.